Non-Spherical Projectiles In Airsoft

[greg]

This discussion is VERY interesting because it seems you are all saying that for airsoft, hop-up provides greater range than a skirted projectile, wheras in paintball, it's the other way round. I'm going to re-read the posts to try and spot the exact reason / factor of why this happens because I seemed to have missed it. I'm also going to dig up some graphs and tests on range regarding paintball hop vs skirted-ammo vs regular ammo.

Yes, in airsoft, it is generally believed.

 

This is because efficient hop can be applied to the rigid, solid bb.

 

I am not aware that an efficient hop can be applied to a soft shell, containing an emulsified liquid.

 

Even if you could apply backspin to the soft shell, you would then have to worry about the contents. It's kind of like spinning an egg; the spin applied to the external shell, is not applied, to the softer, liquefied interior, in the same way.

 

So in paint ball, where hop is not a viable option, the relatively small benefits gained by a skirted or more streamlined projectile, are possibly worth having.

 

 

Greg.

[derf]

Here is something, unfortunately no "hop" data. I'll have to dig around some more.

 

 

EDIT:

 

Here's something:

 

[greg]

Here is something, unfortunately no "hop" data. I'll have to dig around some more.

Ok, so have a good look at that information & realize what it actually means.

 

They have managed to make a paint ball gun, almost as accurate as an out of the box Marui pistol @ 100 feet.

 

How would applying the same strategy improve airsoft?

 

They claim to have doubled the range. Well, the data tells you a bit more than that. What the chart shows, is that it takes the skirted projectile, longer to slow down, than a regular paint ball. This doesn't necessarily equate to twice the usable range.

 

The chart says nothing about trajectory. Yes, the skirting may improve distance, but you will have to aim at the sky to achieve it. Turning your gun into a mortar.

 

As already said, airsofters can already expect 6" groups at around 100', &, can expect, a flat trajectory, double that distance, with a regular bb.

 

The flat line or bent barrel, is applying hop & would not work in conjunction with anything other than round projectiles.

 

Again, it's either/or. You have a choice; improved accuracy with ballistic drop, or standard accuracy with extended range.

 

 

Greg.

[derf]

Let me outline a series of points:

 

Well, we know from practice that in paintball, the systems that have least to most range (in order) are:

- smoothbore

- hop

- skirted

 

We don't have data to show the extent / proportion of these differences since we lack 2 pieces of data:

- Firing angles

- A test that considers all 3 systems at the same time (same test conditions)

 

Regarding the claim "skirts give greater range than hop" it's been said on this thread (as far as I can see) that statement isn't true for airsoft because:

a: increased size of paintball acts differently with air

b: fluid fill of paintball has an inferior spin effect compared to solid BB's

 

There seems to be some rumour or testing that such non-spherical rounds for airsoft have not been successful. I didn't catch the precise reasons, i might read back and check.

 

Premature Conclusion: We know mostly from general practice and some weak data that in paintball, hop gives less range than skirted rounds. For airsoft, we don't have any such practice OR data. Merely rumour (correct me if wrong). Therefore saying that for airsoft, hop gives more range than skirted rounds, is a considerable assumption. I mean, looking at it from a strict evidence point of view, as opposed to hunches. Yes, in theory the argument for solid BB's having more backspin effect is a good one in my eyes, but there extent to which this is true, we do not know, so we don't know if it's considerable enough to supersede the added range a skirted projectile offers.

[Chimpy]

Premature Conclusion: We know mostly from general practice and some weak data that in paintball, hop gives less range than skirted rounds. For airsoft, we don't have any such practice OR data. Merely rumour (correct me if wrong). Therefore saying that for airsoft, hop gives more range than skirted rounds, is a considerable assumption. I mean, looking at it from a strict evidence point of view, as opposed to hunches. Yes, in theory the argument for solid BB's having more backspin effect is a good one in my eyes, but there extent to which this is true, we do not know, so we don't know if it's considerable enough to supersede the added range a skirted projectile offers.

 

The experimental data you want doesn't exist in the public domain AFAIK.

[Triggerhappychappy]

The horse is dead, leave it alone...

 

Side note- thats a lovely graph the company drew, gimme half an hour and I'll draw up a prettier looking one. Until I see some independant testing to prove that the skirted paintballs fly double the range of normal paintballs (without making any other changes such as trajectory or power output of the marker etc), then people might be interested.

 

I believe the accuracy would probably improve at close range with the skirted round, but once you get out to further distances, I doubt you will see any improvement as the side spin and lack of mass makes the projectile unable to hold its course; paintballs are much heavier and able to resist windsheer and gavity much better.

 

Throw a golf ball into the wind, then throw a pingpong ball; then repeat the test with little fins stuck to the back. You will find that range and accuracy are directly related to the mass of the project.

 

In the case of airguns ( thankyou England wonder ) , .177 pellets have a flatter trajectory which makes them great for hunting and target shooting, but more prone to being blown off course down range; .22 pellets have a more curved trajectory, but are less prone to wind deflection down range- they also impart more stopping power to the prey/ target as they have a great mass and retain their velocity better. The same is true of heavy weight .177 pellets, which offer a great compromise, and .20 pellets too that split the difference between power/trajectory & accuracy. Same reason why snipers may use heavier ammo to get better accuracy and range with a more powerful gun (correct me if Im wrong).

[derf]

Until I see some independant testing to prove that the skirted paintballs fly double the range of normal paintballs (without making any other changes such as trajectory or power output of the marker etc), then people might be interested.

 

I've found some data that you're asking for, but it's not entirely what you're after I think.

 

Today we did some testing on how far paintball guns shoot. Not for "effective breaking distance", just simply how far they will shoot. We took four guns:

 

Tippmann A5 w/ Flatline [hop] @ 285fps (gun wouldn't shoot higher for some reason, tried 4 different tanks and CO2 got it to 285fps) = 289.3 feet

Vanguard Creed [smoothbore] @ 300fps = 305.7 feet

SP-1 w/ Apex [hop] @ 300fps = 325.7

Tiberius Arms T9 shooting First Strike Rounds [skirt] @ 300fps = 517.0 feet

 

[in this case, the skirted system shoots 63% further than the best hop-up system]

 

We shot down a long, dirt road. For the paintball guns, we shot about 4 pods each, just shooting it at all different angles, 25 degree, 35 degree, 45 degrees, 55 degrees, just shot until Willie got a good idea of where they were landing. He set a road cone in the "middle" of the disbursement, and we measured (using one of those rolling wheel measuring devices) from our starting point.

 

Keep in mind, one of the rounds did hit Willie, and broke on his shoulder at 500 feet

 

Pics of the "measuring wheel" are up at Punkworks here- http://www.techpb.com/forum/Index.php?showtopic=54607

 

Video:

[Triggerhappychappy]

I take it the Tiberius arms T9 had a smooth bore, not rifled or anything (no hop obviously)?

 

63% is impressive, but still not double the range, and no mention of real accuracy either- having to aim up in the air to get extra range is a bit dubious (though to be fair that was done with all the guns its seems- paintball artillery, hmm...) to me, and using a diffeent gun for each type of ammo too is abit inconsistant.

 

I still believe range wont improve much when used with a much lighter projectile, and accuracy at long range will at best ~the same, if not worse. You could conduct a fair test buy using some form of single shot homebrew air cannons- stick normal round ball down the barrel and record accuracy and range results with targets places at various distances- sight the barrel in using a laser so you know you are aiming dead center, then fire away (normal hop fitted). Then repeat the test with no hop. If someone has a spare gearbox and barrel floating around, they could make a test rig- just neeed to source some of those rare finned bbs.

[derf]

Yeah, the T9 is smooth bored and no hop.

 

Sure, the test is fairly crude for the discussion of practical range and accuracy especially.

 

You're right, what we need is a test. It seems a fairly easy test to design really. The hardest part will be finding / producing a few dummy non-spherical BB's. I can do this fairly easily with rapid prototyping but I need to action alot of things to get started and given I don't even play airsoft, I may not be the best bloke to do it. Having said that, if I decided before next Summer to get into airsoft, i'm pretty certain i'll play around with this idea and publish the results.

[EmptyChambers]

Just out of curiosity, whats the point of extending the range of paintballs? Having worked at a field for a few summers, despite not playing, I can tell you that while the flatline/ LRB style barrels did extend the range, the projectiles lacked the velocity to splatter at any distance beyond what they would have dropped off at with a normal barrel anyways. Surely a skirted/rotating ball will do the same, energy retention not withstanding.

 

To flog on it a bit more, we don't NEED to change from hopup. If many more intelligent and qualified designers decided it wasn't worth the cost for marginal improvements, they likely have had more time and money with which to test, than a few forumites puffing their chest out about how they have the biggest newest thing to hit airsoft...

[teflon don]

i have read trough some of these post and the first thing that i would like to say is

range doesn't mean *suitcase* if you are not accurate

secondly you don't need a hop up

here the math

if a bb traveling 300fps(average) will only drop 9.81 meter over 100meter thats 5°36' you can compensate that with a scope

 

When a bullet spins along its axis it does nothing for lift.

actually it does

if you fire with crosswind you can have positive and negative lift depending on where the wind comes from

i know that is useless

 

What it DOES do is control the motion of the BB in a predicable, repeatable way which means the shooter gets far less surprises from BBs doing unexpected things during flight.

there are alot of factors that can affect backspin with a hop up youll always have bb that fly off or cure you won't have that problem if you would have rifling or fins

the only reason that bb apaer to be stable is because they have alot of momentum once it loses some of that momentum they became less predictable

 

Because the BB is spinning backwards friction means it's easier for air to flow over the top half of the BB than it is to flow over the bottom half.

This means the air is denser underneath the BB and lift is generated.

the air density doesn't change

air is forced over the bb that makes the air travel faster and that creates a low pressure zone above the bb

 

the reason that non spherical projectals aren't used is because of the cost and it a big step to switch over

they don't make the bb because there aren't any guns that use them and they don't build any guns that use them because there aren't any bb

[derf]

@ Empty

 

Paintballs not breaking at extended ranges is down the the consistency of the shell. The new skirted paintballs break perfectly fine at max range because their nose is designed to be brittle enough to withstand stress from being fired but break upon max range impact.

 

Your second paragraph is mainly invalid from an economics point of view. How are you able to tell what airsoft "needs"? How do you know that designers turned this very idea down, and the reasons to which they did including the efforts and tests and results they attempted? Perhaps there was a conflict of interest? Perhaps there were funding issues? Perhaps the tests were flawed? We don't know.

 

@ Teflon

 

That's my first impression too. Economic reasons mainly.

[derf]

I've done some more digging. Actually this is just from the RAP forum regarding "Airfin":

 

we are looking at 300+ feet accuracy

 

Q - What velocity will you need in order to get 300 feet of range?

A - 400fps

 

I don't know what these figures mean in airsoft. Maybe someone can put this into perspective?

 

[Stealthbomber]

here the math

if a bb traveling 300fps(average) will only drop 9.81 meter over 100meter thats 5°36' you can compensate that with a scope

Here is the common sense.

Aiming 10m above your intended target is not practical.

 

if you fire with crosswind you can have positive and negative lift depending on where the wind comes from

i know that is useless

 

 

there are alot of factors that can affect backspin with a hop up youll always have bb that fly off or cure you won't have that problem if you would have rifling or fins

the only reason that bb apaer to be stable is because they have alot of momentum once it loses some of that momentum they became less predictable

Nonsense.

 

The hop-up applies a consistant spin on each BB which means that (variations in BB construction aside) each BB will act predicably when it leaves the barrel.

 

Assuming that a skirted or finned BB is made to the same tolerences as a normal one it will suffer exactly the same issues.

If a finned BB is made "perfectly" then a regular BB also made to the same standard would also show improved characteristics, be simpler to manufacture, require no modifications to an airsoft gun and also be able to make use of a hop-up.

 

the air density doesn't change

air is forced over the bb that makes the air travel faster and that creates a low pressure zone above the bb

Eh?

 

You say the air density doesn't change and then go on to say that there's a "low pressure zone" above the BB?

 

the reason that non spherical projectals aren't used is because of the cost and it a big step to switch over

they don't make the bb because there aren't any guns that use them and they don't build any guns that use them because there aren't any bb

I disagree.

 

I suspect that the reason finned BBs aren't used is because any advantage they might offer will be less than the advantage offered by a hop-up system.

[galactica]

i have read trough some of these post and the first thing that i would like to say is

range doesn't mean *suitcase* if you are not accurate

secondly you don't need a hop up

here the math

if a bb traveling 300fps(average) will only drop 9.81 meter over 100meter thats 5°36' you can compensate that with a scope

Funniest thing i've seen on these forums. Amazing.

[Azulsky]

What is the point for increasing the range of an airsoft gun more than current capable when you can already start to dodge shots at max range.

[derf]

Because they may not have seen you.

[Kristoffer]

TDS speaks of other players not beeing able or skilled enough or simply too lazy to use a non-hopped gun, and others talk about shooting at 25 degrees and more to get range.

 

How often do real snipers shoot at an angle that is so steep that their target isn't even in their scope? A hopped rifle will very rarely let you shoot a 300" flat shot where the BB is in the centre of the crosshairs of your scope from the nozzle of your gun and 300feet down range(I have never seen a rifle like this, but I suppose someone will claim the opposite).

 

A hopped rifle shooting a heavy BB will let you shoot a realistic shot, where you can use mil-dots or any other range-adjustment you might have in your scope to compensate for longer shots.

 

 

 

[teflon don]

Aiming 10m above your intended target is not practical.

aiming 5° higher isn't that difficult

you can ad a small spacer under your rail

another thing i used 300fps for easy calculation generaly a sniper shoots alot harder and bullet drop will increase exponential with time so if the flight time is half as much the bullet drop will be far less

if it shoots 600fps the bullet drop will be 2.45 meter thats 1°24'

 

rolleyes.gif

you can roll your eyes as much as you want it doesn't change the fact that im right and hes wrong

 

The hop-up applies a consistant spin on each BB which means that (variations in BB construction aside) each BB will act predictably when it leaves the barrel.

no it doesn't

vibrations can change the hop up setting oil or dirt can reduce friction whet bucking will wear out over time heat also affect the properties of rubber

humidity can affect the rubber

 

rifling will make an exact amount of rotation over an exact distance

 

 

You say the air density doesn't change and then go on to say that there's a "low pressure zone" above the BB? rolleyes.gif

density and presure are 2 different things

 

 

I suspect that the reason finned BBs aren't used is because any advantage they might offer will be less than the advantage offered by a hop-up system.

its probably a mix a factors

but why did asahi chose for blade bb instead a hop up

[tome]

I haven't bothered to do the maths (because i suspect neither have you) but i doubt there's any airsoft sniper rifle from which a bb will do an average of 600 fps in its effective range. I suspect it would require a muzzle velocity somewhat higher than what is legal. If it was really that simple, why on earth did they bother inventing the hop up system in the first place? Do you use your airsoft guns without hop on at skirmishes?

 

As for rifling producing an exact amount of twist. If you tried to rifle an airsoft projectile, what makes you think that dirt and other debris or even lubrication in the barrel won't affect the amount of twist. I'm pretty sure you wouldn't practically be able to rifle a 6mm plastic projectile so the point is... well.... pointless.

[Stealthbomber]

vibrations can change the hop up setting oil or dirt can reduce friction whet bucking will wear out over time heat also affect the properties of rubber

humidity can affect the rubber

 

rifling will make an exact amount of rotation over an exact distance

This is EXACTLY the sort of subjective nonsense that subjects like this proliferate.

 

You've just mentioned a bunch of stuff that "might" cause a hop-up to be inconsistent and then, with your next breath, make an arbitrary statement which you blindly accept as the truth without considering if the same issues will also apply to the alternative as well.

 

density and presure are 2 different things

When you alter the pressure of air you change the density of it as well.

 

but why did asahi chose for blade bb instead a hop up

More to the point, what happened to them?

[Docv400]

...secondly you don't need a hop up

here's the math;

If a bb traveling 300fps(average) will only drop 9.81 meter over 100meter thats 5°36' you can compensate that with a scope...

So a BB fired at 300fps will still be doing 300fps after 100m?

Think again.

It most likely won't even reach 100m.

It'll be down to approx <90fps after just 30m (98ft)

Check out the tables here...

 

there are alot of factors that can affect backspin with a hop up youll always have bb that fly off or curve you won't have that problem if you would have rifling or fins

the only reason that bb apear to be stable is because they have a lot of momentum once it loses some of that momentum they became less predictable

Yes, a few shots may not go where expected (more often than not due to BB quality/consistency), but the vast majority will, as long as your AEG (or whatever) is well maintained and properly set up.

 

A finned projectile (or one spun by rifling) will lose momentum just like any other, regardless of shape.

Having fins on a projectile (or spinning a finless projectile) only stabilises it's flight.

 

Any (non-powered) projectile, fired horizontally over level ground, from any weapon, will hit the ground as quickly as one that's simply dropped from the same height as the gun it's fired from.

Gravity works the same on an object whether it's travelling at mach 1, or it's just dropped from your hand.

 

I don't want to have to shoot at a point way above my intended targets to hit them.

I'll just keep on aiming directly at them, within my various weapons' accurate ranges (30-50m), thank you

[teflon don]

I haven't bothered to do the maths (because i suspect neither have you)

do the math

because what you are saying now is that you have no idea what you are talking about

do you want to check my math ? i can send you my formulas

but i doubt there's any airsoft sniper rifle from which a bb will do an average of 600 fps

thats why i used 300fps in my first example

remember that a finned bb will decelerate slower that a regular bb

I suspect it would require a muzzle velocity somewhat higher than what is legal

8joules is the legal limit in belgium

anyway i guess that if you want 300fps average you might only need 400fps muzzle velocity

why on earth did they bother inventing the hop up system in the first place

because its the best that they could do a that time

and its easier than adding rifling to barrels and it uses bb that are easy to mass produce

what makes you think that dirt and other debris or even lubrication in the barrel won't affect the amount of twist. I'm pretty sure you wouldn't practically be able to rifle a 6mm plastic projectile so the point is... well.... pointless.

because the bb will turn in the same way as the rifling so if the rifling doesn't change the bb will come out of the barrel in the same way each time

why wouldn't you be able to rifle them plastic is softer than metal so the bb will take the shape of the barrel like a bullet would do in a real gun

[Stealthbomber]

I think it's time we raised the issue of whether a person can be suspended or banned simply for gross ignorance?

[Rob15]

why wouldn't you be able to rifle them plastic is softer than metal so the bb will take the shape of the barrel like a bullet would do in a real gun

The reason you can't do that is because real bullets have a huge amount more power behind them, according to wiki a 5.56 4g round has 1,767 J, thats 1,767 times more than your average AEG has.

 

EDIT : Plastic is softer than metal? Thats a bit of a vague statement isn't it? Some plastics are harder than some metals.